Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
h,w=map(int,input().split())
s=['#'*(w+2)]
s+=['#'+input()+'#' for _ in range(h)]
s.append('#'*(w+2))
h+=2
w+=2
p=[[1,0],[0,1],[-1,0],[0,-1]]
st=[]
cnt=0
for i in range(h):
    for j in range(w):
        if s[i][j]=='.':
            cnt+=1
ans=0
n=[(1,1)]
route={n[0]:0}
count=0
while n:
    count+=1
    n2=[]
    for i in n:
        for j in p:
            np=(i[0]+j[0],i[1]+j[1])
            if s[np[0]][np[1]]=='.' and route.get(np,-1)==-1:
                n2.append(np)
                route[np]=count
    n=n2
if route.get((h-2,w-2),-1)>=0:
    print(cnt-route.get((h-2,w-2),-1)-1)
else:
    print(-1)